1. Field of the Invention
The present invention is directed to the use of long chain alkyl ester copolymers as emulsifiers and stabilizers for water base emulsions and dispersions of hydrocarbonaceous materials. In particular, the present invention is directed to the use of copolymers of unsaturated carboxylic acid and long chain alkyl ester in the formation of such stable emulsions and dispersions. The emulsifier stabilizers of the present invention have specific utility in cleaning oil contaminated vessels, oil spill management, enhanced oil recovery by chemical flooding and the transportation and storage of heavy crude oil-water mixtures and coal-water slurries.
2. Description of the Prior Art
The use of surfactants or emulsifiers to produce stable emulsions or dispersions of various hydrocarbonaceous materials in water have been attempted in the prior art.
For example, ordinary surfactants or emulsifiers have been used to produce oil-in-water emulsions. Ordinary surfactants, generally, are compounds which have a low molecular weight (e.g. less than 30 carbon atoms) and contain hydrophilic (water loving) and lipophilic (oil-loving) groups. When a mixture of oil and water is mechanically sheared in the presence of these types of surfactants, the surfactants distribute themselves at the oil-water interface as the droplets of oil are formed thus facilitating the formation of an oil-in-water emulsion. Because of the faster mobility of the low molecular weight surfactants, they are quite effective in forming an initial emulsion of the oil and water. However, when the mechanical shear is removed and the emulsion is allowed to stand for some time (i.e. a few hours, days) most emulsions made from this type of surfactant tend to separate. The reason attributed to the separation is because the mobility of the surfactants are such that they move in and out of the surface of the oil droplets leaving some surface area of the oil droplets exposed. Accordingly, when two oil droplets collide at an exposed site, coalescence of the droplets occurs. As time goes on, larger and larger droplets of oil are formed resulting in the separation of the oil phase from the water phase. This same principle also is applicable to coal-in-water dispersions. Coal particles suspended in such a mixture will collide and agglomerate over time. As the agglomerates become larger, they become too heavy to remain suspended in the mixture and settle to the bottom of the mixture. Accordingly, to stabilize the emulsions and dispersions of hydrocarbonaceous materials in water the use of a surfactant which is not mobile would be highly desirable.
In U.S. Pat. No. 4,311,832 to Gutnick et al., a naturally occurring long chained material suitable for emulsions stabilization of oil-in-water emulsions is disclosed. The material is identified as "EMULSAN". The emulsion stabilizer properties of "EMULSAN" arise from its unique structure which consists of a large molecular weight molecule containing both hydrophilic and lipophilic groups. The large molecular weight of the emulsan molecule is such that once the molecules have attached themselves to the oil water interface they tend to stay there resulting in a highly stable emulsion. While emulsions produced by the use of "EMULSAN" have exhibited high stability they are produced by biotechnological procedures which are relatively inflexible because of their dependence on bacteria to make the product. Accordingly, the use of a synthetic high molecular weight material as a emulsion stabilizer would be highly preferable because it may be modified or produced by various procedures giving the molecule a significant flexibility not possessed by the biotechnological product.
U.S. Pat. No. 3,915,921 to Schlatzer discloses unsaturated carboxylic acid-long chain alkyl ester copolymers and terpolymers useful as water thickening agents and emulsifiers. The patent is directed to the formation of a thickener which is not ion sensitive and serves to efficiently maintain or increase the viscosity of water or organic solvent solutions containing inorganic salts such as sodium chloride. In part, the disclosure of this patent is directed to copolymers of between 50 and 95 percent by weight of an unsaturated carboxylic acid and between 5 and 50 percent by weight of a long chain alkyl esters. These copolymers are disclosed to be emulsifying agents for water-solvent compositions.
It is the primary object of the present invention to provide a polymer possessing emulsifying and stabilizing properties for use in production of stable emulsions and dispersions of hydrocarbonaceous materials in water. It is a further object of the present invention to provide a novel stable oil-in-water emulsion and coal-in-water dispersions.